Factor analysis of obesity, diabetes, hypertension and syndrome X in the Jackson Heart Study cohort

Background— Clustering of cardiovascular (CV) risks believed to contribute to the rising burden of debilitating and life-threatening disorders, the increasing rates of obesity and type 2 diabetes, and the growing importance of metabolic syndrome, have made assessment of CV risk clustering an urgent undertaking. Though these diseases often cluster in individuals and families, the basis of their aggregation is not well known.

Objective: This study was designed to understand the pathogenesis of Syndrome X and determine what independent factors can be extracted to better fit and explain the total variance of obesity, diabetes, hypertension and Syndrome X among African Americans.

Methods— Exploratory factor analysis (principal components analysis) was performed with data from 5301 African-American participants in the Jackson Heart Study (JHS)using the Factor procedure in SAS. Measured variables included sex, age at Exam 1,fasting triglyceride level, total cholesterol, LDL cholesterol, fasting glucose, waist circumference, neck circumference, systolic blood pressure, diastolic blood pressure,hemoglobin A1C, glomular filtration rate (measure of renal function). The squared multiple correlation was used as the communality estimate for each variable and the varimax orthogonal rotation procedure was applied.

Results -Factor analysis yielded 4 principal factors that explained approximately 95.4% of the total variance: Factor 1, cholesterol; factor 2, age and diabetes measures; factor 3,neck circumference; factor 4, age and cholesterol measures, with a negative loading for LDL, and systolic blood pressure.

Conclusions—We speculate that factor 3 might be related to obstructive sleep apnea and factor 4 may be related to atherosclerosis.